Photocatalytic cement composite surface reactivation impact on the degradation rate of methylene blue in a circulating flow fixed-bed photoreactor

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The use of polymers or ceramics as a fixed-bed in photoreactors, other than causing complexities and environmental pollution, imposes high costs on treatment systems. This study used photocatalytic cement composite as a practical and economic material for a bed. To evaluate the impact of cement matrix characteristics on the photocatalytic activity of the bed surface, six different mix designs with two water binder ratio of 0.28 and 0.42 was considered. Furthermore, 0%, 5% and 10% of cement content was replaced by silica fume. In addition, the effect of acid treatment on increasing the degradation rate of methylene blue was investigated. Standard tests were performed to determine the mechanical properties of the composites, and spectroscopic tests were carried out to evaluate the changes in methylene blue concentration on the extracted samples. In addition, improving the mechanical properties of the composite did not lead to a significant decrease in the performance of photocatalytic treatment. Due to their higher abrasion resistance, high-performance composites are considered efficient materials in terms of durability and pollution. The microstructural evaluation also proved the role of acid treatment in increasing the contact surface and TiO 2 particles' appearance on the composite surface.